An inter-laboratory comparison demonstrates that [1H]-NMR metabolite fingerprinting is a robust technique for collaborative plant metabolomic data collection

In any metabolomics experiment, robustness and reproducibility of data collection is of vital importance. These become more important in collaborative studies where data is to be collected on multiple instruments. With minimisation of variance in sample preparation and instrument performance it is possible to elucidate even subtle differences in metabolite fingerprints due to genotype or biological treatment. In this paper we report on an inter laboratory comparison of plant derived samples by [1H]-NMR spectroscopy across five different sites and within those sites utilising instruments with different probes and magnetic field strengths of 9.4 T (400 MHz), 11.7 T (500 MHz) and 14.1 T (600 MHz). Whilst the focus of the study is on consistent data collection across laboratories, aspects of sample stability and the requirement for sample rotation within the NMR magnet are also discussed. Comparability of the datasets from participating laboratories was exceptionally good and the data were amenable to comparative analysis by multivariate statistics. Field strength differences can be adjusted for in the data pre-processing and multivariate analysis demonstrating that [1H]-NMR fingerprinting is the ideal technique for large scale plant metabolomics data collection requiring the participation of multiple laboratories

Ann Intensive Care

Despite a large body of evidence, the implementation of guidelines on hemodynamic optimization and goal-directed therapy remains limited in daily routine practice. To facilitate/accelerate this implementation, a panel of experts in the field proposes an approach based on six relevant questions/answers that are frequently mentioned by clinicians, using a critical appraisal of the literature and a modified Delphi process. The mean arterial pressure is a major determinant of organ perfusion, so that the authors unanimously recommend not to tolerate absolute values below 65 mmHg during surgery to reduce the risk of postoperative organ dysfunction. Despite well-identified limitations, the authors unanimously propose the use of dynamic indices to rationalize fluid therapy in a large number of patients undergoing non-cardiac surgery, pending the implementation of a "validity criteria checklist" before applying volume expansion. The authors recommend with a good agreement mini- or non-invasive stroke volume/cardiac output monitoring in moderate to high-risk surgical patients to optimize fluid therapy on an individual basis and avoid volume overload. The authors propose to use fluids and vasoconstrictors in combination to achieve optimal blood flow and maintain perfusion pressure above the thresholds considered at risk. Although purchase of disposable sensors and stand-alone monitors will result in additional costs, the authors unanimously acknowledge that there are data strongly suggesting this may be counterbalanced by a sustained reduction in postoperative morbidity and hospital lengths of stay. Beside existing guidelines, knowledge and explicit clinical reasoning tools followed by decision algorithms are mandatory to implement individualized hemodynamic optimization strategies and reduce postoperative morbidity and duration of hospital stay in high-risk surgical patients

Analysis of enzyme activities

The evaluation of enzyme activities, especially their capacities, represents an important step towards the modelling of biochemical pathways in living organisms. The implementation of microplate technology enables the determination of up to >50 enzymes in relatively large numbers of samples and in various biological materials. Most of these enzymes are involved in central metabolism and several pathways are entirely covered. Direct or indirect assays can be used, as well as highly sensitive assays, depending on the abundance of the enzymes under study. To exemplify such methods, protocols for UDP-glucose pyrophosphorylase (E.C. 2.7.7.9) operating in real time and for pyrophosphate:fructose-6-phosphate 1-phosphotransferase (E.C. 2.7.1.90) are presented

a multi-scale perspective centered on fruit

Fruit development, from its early stages, is the result of a complex network of interacting processes, on different scales. These include cell division, cell expansion but also nutrient transport from the plant, and exchanges with the environment. In the presence of nutrient limitation, in particular, the plant reacts as a whole, by modifying its architecture, metabolism, and reproductive strategy, determining the resources available for fruit development, which in turn affects the overall source-sink balance of the system. Here, we present an integrated model of tomato that explicitly accounts for early developmental changes (from cell division to harvest), and use it to investigate the impact of water deficit and carbon limitation on nutrient fluxes and fruit growth, in both dry and fresh mass. Variability in fruit response is analyzed on two different scales: among trusses at plant level, and within cell populations at fruit level. Results show that the effect of stress on individual cells strongly depends on their age, size, and uptake capabilities, and that the timing of stress application, together with the fruit position on the plant, is crucial in determining the final phenotypic outcome. Water deficit and carbon depletion impacted either source size, source activity, or sink strength with contrasted effects on fruit growth. An important prediction of the model is the major role of symplasmic transport of carbon in the early stage of fruit development, as a catalyst for cell and fruit growth

a multi-scale perspective centered on fruit

Fruit development, from its early stages, is the result of a complex network of interacting processes, on different scales. These include cell division, cell expansion but also nutrient transport from the plant, and exchanges with the environment. In the presence of nutrient limitation, in particular, the plant reacts as a whole, by modifying its architecture, metabolism, and reproductive strategy, determining the resources available for fruit development, which in turn affects the overall source-sink balance of the system. Here, we present an integrated model of tomato that explicitly accounts for early developmental changes (from cell division to harvest), and use it to investigate the impact of water deficit and carbon limitation on nutrient fluxes and fruit growth, in both dry and fresh mass. Variability in fruit response is analyzed on two different scales: among trusses at plant level, and within cell populations at fruit level. Results show that the effect of stress on individual cells strongly depends on their age, size, and uptake capabilities, and that the timing of stress application, together with the fruit position on the plant, is crucial in determining the final phenotypic outcome. Water deficit and carbon depletion impacted either source size, source activity, or sink strength with contrasted effects on fruit growth. An important prediction of the model is the major role of symplasmic transport of carbon in the early stage of fruit development, as a catalyst for cell and fruit growth

La pêche et l’ostréiculture dans les pertuis Charentais à l’aube des années 2000. Dynamique des exploitations et système de gestion

In 2000, and after a long period of gestation, an offshore oyster farming experiment, on depths of 10 to 20 meters, started in the Pertuis Charentais. It faced strong opposition from fishermen, without the unanimous support of oyster farmers. In this context, an analysis of the rationalities in place seemed to be able to help to better understand the positions of the various actors. Monographies of fishing and oyster firms have been carried out using methods developed for family farms. Following them, so-called functioning typologies have classified the farms according to their evolution capacities. This part of the study was completed by an analysis of the management system for fisheries and shellfish culture in Pertuis Charentais. It highlighted its weak ability to drive change. The possibility of improving this capacity through approaches such as, for example, the practice of prospective reflection exercises is suggested in conclusion.  En 2000, et après une longue période de gestation, un essai d’ostréiculture hors estran, sur des fonds de 10 à 20 mètres, a débuté dans les pertuis Charentais. Il s’est heurté à une forte opposition des pêcheurs, sans pour autant bénéficier d’une adhésion unanime au sein des ostréiculteurs. Dans ce contexte, une analyse des rationalités à l’œuvre a paru pouvoir apporter une aide pour mieux faire comprendre les positions des différents acteurs. Des monographies des exploitations de pêche et ostréicoles ont pour cela été réalisées en s’appuyant méthodes formalisées pour les exploitations familiales agricoles. À leur suite, des typologies dites de fonctionnement ont classé les exploitations selon leurs capacités d’évolution. Ce volet de l’étude a été complété par une analyse du système de gestion des pêches et de la conchyliculture dans les pertuis Charentais. Il a mis en évidence sa faible aptitude à piloter les changements. La possibilité d’améliorer cette capacité par des démarches telles que par exemple, la pratique d’exercices de réflexion prospective est suggérée en conclusion

Influence of complexation between amylose and a flavored model sponge cake on the degree of aroma compound release

International audienceFlavoring is used in the food industry to reinforce the aroma profile of baked cereal goods. During the processing of such products, interactions between starch and aroma compounds can occur, and this may have an impact on aroma release and perception. In the present study, 20 aroma compounds were tested to establish whether they formed complexes with amylose. The structure of the complexes was determined by wide-angle X-ray scattering (WAXS). A cocomplexation study proved that several complexing compounds could be present in the same crystalline aggregate. WAXS and differential scanning calorimetry (DSC) experiments were performed in a flavored model sponge cake at different steps of processing and showed that aroma compounds might form complexes with amylose in a sponge cake as they can do in simple system containing only amylose. Some of the aroma compounds trapped in the sponge cake were quantified, and their release behavior was followed by headspace analysis. The V-type structure could partly explain aroma retention in the product and the rate of aroma release

Magnetic micropillars as a tool to govern substrate deformations

International audienceMagnetic actuated microdevices can be used to achieve several complex functions in microfluidics and microfabricated devices. For example, magnetic mixers and magnetic actuators have been proposed to help handling fluids at a small scale. Here, we present a strategy to create magnetically actuated micropillar arrays. We combined microfabrication techniques and the dispersion of magnetic aggregates embedded inside polymeric matrices to design micrometre scale magnetic features. By creating a magnetic field gradient in the vicinity of the substrate, well-defined forces were applied on these magnetic aggregates which in turn induced a deflection of the micropillars. By dispersing either spherical aggregates or magnetic nanowires into the gels, we can induce synchronized motions of a group of pillars or the movement of isolated pillars under a magnetic field gradient. When combined with microfabrication processes, this versatile tool leads to local as well as global substrate actuations within a range of dimensions that are relevant for microfluidics and biological applications